1. Field of the Invention
The present invention relates to a method of forming a material layer applicable to the field of electronics and a method of manufacturing an electronic device using the method of forming the material layer.
2. Description of the Related Art
Various types of electronic material layers are used in the field of electronics. Electronic material layers are formed of a material such as a conductive material or a semiconductor material, and are designed and manufactured in various patterns according to devices to which the electronic material layers are applied.
Electronic material layers are generally subjected to a film forming process, and some of the electronic material layers are subjected to a subsequent patterning process to have a desired shape.
Methods of forming a film may include a method of directly forming an electronic material layer on a target object and a method of forming an electronic material layer on an intermediate object and then transferring the electronic material layer to a target object.
A conductive thin film, which is an electronic material layer, is considered as an important element in display, antistatic, electrostatic dissipation, and so on. In particular, extensive research has been conducted on the use of a carbon nanotube (CNT) thin film in a heater and a thermal radiator because the CNT thin film has high electrical conductivity and high thermal conductivity.
Since CNTs have good charge transfer characteristics and a high aspect ratio, CNTs have high charge mobility and transparency, so as to obtain a plurality of charge transfer paths. Also, since CNTs have high elasticity, the CNTs are electrically and mechanically stable to bending. Accordingly, research on the use of CNTs as a material for a conductive thin film has been conducted.
Methods of manufacturing a CNT thin film may be roughly divided into a method of directly forming a thin film on a substrate by using a liquid medium in which CNTs are dispersed, and a method of growing CNTs and then transferring the CNTs to a substrate. Examples of the former method may include filtration, spraying, roll-to-roll processing, bar coating, dielectrophoresis, and inkjet printing. Since a thin film formed by the former method is affected by the state of a surface of a substrate or a material of the substrate, the quality of the thin film may vary according to the state of the substrate. Examples of the latter method mostly using a CNT thin film formed on a substrate made of silicon (Si) by chemical vapor deposition (CVD) may include transfer printing, such as stamping, and CNT separation using a sacrificial layer. Transfer printing has disadvantages in that undesired impurities may penetrate into a CNT thin film during a transfer process that uses a metal and a polymer, and a plurality of processes are required, thereby increasing manufacturing costs. CNT separation using a sacrificial layer involves forming a sacrificial layer made of SiO2 or the like on a substrate made of Si during CNT synthesis, growing CNTs on the sacrificial layer, and removing the sacrificial layer to obtain a CNT thin film. The CNT separation using the sacrificial layer has a disadvantage in that since the yield of the CNT thin film formed by the CNT synthesis is low, there is a limitation in using the CNT separation and productivity is low.
Accordingly, it is preferable to directly form a CNT thin film on a substrate by using a CNT suspension in which synthesized CNTs are dispersed. However, since a conventional method of directly forming a CNT thin film on a substrate uses a liquid medium so that CNTs are attached to a substrate while a solvent is evaporated, the degree of dispersion of the CNTs in the liquid medium is reduced during the evaporation of the solvent, thereby degrading the quality of the CNT thin film. Accordingly, there is a demand for a method of manufacturing and transferring a CNT thin film which can rapidly remove a solvent.